Automatic pickup for stacking material



Dec. 10, 1963 A. G. TUCCI 3,113,771

AUTOMATIC PICKUP FOR STACKING MATERIAL Filed Feb. 20, 1962 5Sheets-Sheet 1 :0 Motor 2 2;:

A To Clamp Arm /5 [NVENTOR fi P19. 2. i

A. G. TUCCI AUTOMATIC PICKUP FOR STACKING MATERIAL Dec. 10, 1963 5Sheets-Sheet 2 Filed Feb. 20, 1962 INVENTOR I Anthon G.Tucci Fig. 3.

Dec. 10, 1963 A. G. ucc 3,113,711

AUTOMATIC PICKUP FOR STACKING MATERIAL Filed Feb. 20, 1962 5Sheets-Sheet 3 Fig.4.

Dec. 10, 1963 A. G. TUCCI 3,1 3 77 AUTOMATIC PICKUP FOR STACKINGMATERIAL Filed Feb, 20, 1962 5 Sheets-Sheet 4 Dec. 10, 1963 A. G. TUCClT 3,113,771

AUTOMATIC PICKUP FOR STACKING MATERIAL Filed Feb. '20. 1962 5Sheets-Sheet 5 Fig. 6.

INVENTOR Anthony G. Tucci United States Patent 3,113,771 AUTOMATICPICKUP Ffiii STACKING MA'KEREAL Anthony G. Tucci, 9692 am Ave, (izonePark, N.Y. Filed Feb. 2t}, 1962, Ser. No. 174,569 11 Claims. (Cl.270-61) This invention relates to a device for receiving and stacking orotherwise handling a succession of flexible articles or a continuous runof flexible material. In particular, this invention relates to anautomatic device for receiving cloth workpieces discharged from apressing machine or the like.

Many devices have been proposed for the purpose of receiving andstacking workpieces or material discharged from an apparatus performingone operation or another on such material. For example, many deviceshave been proposed for stacking cardboard carton blanks discharged fromthe cutting machine, for (receiving and stacking printed matter as itemerges from the printer, and for similar purposes.

In the handling of fabric workpieces, however, the problem is somewhatdifferent because of the nature of the fabric itself. Thus, machines ofthe type employed in the manufacture of cardboard carton blanksgenerally depend for their proper functioning on the stiffness of thecardboard material. Similarly, machines designed to handle paperworkpieces such as printed matter also usually depend on the relativestiffness of the paper which, although much less than that of cardboard,is nevertheless appreciable in an edgewise direction. Such machinescannot be successfully employed in connection with a comparatively limpmaterial such as cloth.

In addition, previously-suggested means of the type described have ingeneral been of very complicated construction, and were consequentlycostly to build and expensive to maintain, and subject to failurebecause of the large number of working parts involved. For these andother reasons, the garment industries have generally not employed pickupor stacking machines for the purpose indicated, but have been forced tothe expense of employing manual labor for the purpose, because there hasnot been any machine available that was equal to the job.

Aside from the stacking of individual workpieces, it is sometimesnecessary to deal with a continuous length of material, such as a seriesof workpieces which are connected together. In the modernmass-production garment factory, it is customary to employ amodification of the well-known assembly-line technique, whereby a seriesof garments made from various materials is made by first cutting thevarious pieces, running them through the various required operations inthe same order in which they were cut, and subsequently reassembling thevarious partly-finished pieces for final assembly into finishedgarments. In order for this type of operation to be successful, it isessential that the various pieces in any one operation (representingcorresponding pieces from a series of different garments), retain theirrelative order. Otherwise, the final assembly point would quickly becomecluttered with incomplete units, each waiting for one or another of itscomponents to reach the assembly point, and the result would be chaos.In practice, the preferred and most economical way of preserving theproper order is to string successive pieces together with the sewingmachine, and to leave the strings intact until they reach the assemblypoint. For a pickup or stacking device to be completely satisfactory,therefore, it should be capable of accommodating pieces which are strungtogether in the manner described, and the machines which have beensuggested up to the present in general lack this capability.

In some operations, it is desirable for the operator of the machine, forexample a pressing machine, to be able to pick up the workpiece after hehas performed an operation on it, for example a pressing operation, andeither perform a second operation on the same workpiece or dispose of itotherwise as the requirements of the process may dictate. In manyinstances, this is rendered impossible by the design of the machine,which discharges the workpiece at a point remote from the operator, whois normally stationed at the feed end of the machine. This situationobviously necessitates providing an additional operator near thedischarge point, unless a suitable auxiliary apparatus is provided 'toreturn the workpiece from the discharge end of the presser, or the like,to a point near the operator. To date, no satisfactory auxiliaryapparatus has existed.

An object of this invention, therefore, is to provide an improved typeof pickup device. Another object is to provide a pickup device capableof handling limp materials such as textile fabrics and the like. Stillanother object is to provide a pickup device capable of automaticallyand accurately stacking continuous lengths of material folded repeatedlyupon itself. Another object is to provide a device of the type describedwhich is simple in construction and operation, and inexpensive to buildand maintain. A further object is to provide such a device, which iscapable of accommodating successive workpieces which are strungtogether. A still further object is to provide a device adapted toreceive a workpiece from a machine at a discharge point remote from theoperator of said machine, and deliver said workpiece back to a pointnear said operator.

Other objects and advantages will become apparent from the followingmore complete description and claims, and with reference to theaccompanying drawings, in which:

'FiG. 1 is a perspective view of one embodiment of the invention;

FIG. 2 is a plan view of a detail of the clutch mechanism of theembodiment shown in FIG. 1;;

FIG. 3 is a plan view of another detail similar to PEG. 2, showing analternative type of clutch mechanism;

FIG. 4 is a perspective view of a preferred form of stacking table foruse in conjunction with the embodiment shown in FIG. 1;

FIG. 5 is a perspective view, partially diagrammatic, of an embodimentof the invention adapted to the folding or laying-up of continuouslengths of material;

*FIG. 6 is a perspective view, partially diagrammatic, of an embodimentof the invention adapted to return each piece discharged from theseamresser or other machine to a point near the operator thereof.

FIG. 7 is a diagrammatic representation of a stacking table providedwith a preferred type of height adjustment mechanism.

In FIG. 1, there is shown a belt 11, which is part of the mechanism ofan associated machine for example a seam-presser. Workpiece 12, as it isdischarged from the belt, intercepts a light and photocell assemblywhich (through a relay if required) actuates solenoid 13 (electricalconnections not shown). The plunger of solenoid 13 presses against clamp14, causing it to engage with the lower run of belt 11. This causesclamp arm 15 to move to the right about pivot 16 at its lower end,against the tension of spring 17. The movement of the clamp arm istransmitted through a suitable linkage (not shown in this view) to areversing disc clutch which is so arranged that when arm 15 moves to theright, the clutch is engaged so as to move drum 20 in a counterclockwisedirection. Cable 21, which is fixed at both ends, is looped over drum2%) in such a way that counterclockwise rotation of drum 2% causes thepickup device as a whole to roll to the right.

If the speed of the carriage to the right exceeds that of the belt,clamp arm 15 tends to return to a vertical position, which, through theabove-mentioned linkage, results in relaxing the pressure on the facesof the disc clutch, permitting enough slippage to adjust the speed ofthe carriage to that of the belt. The result of this synchronization isthat the workpiece is paid out onto the pickup table in fiat form. Thepickup table surmounts the carriage and travels back and forth with it,and is shown in dotted outline in FIG. 1.

When the end of the workpiece has passed the photocell assembly, thelight again falls on the photocell with the result that solenoid 13 isdeactivated, releasing the clamp from the belt. This permits spring 17to move the clamp arm through the vertical to a position on the left,and this positioning of the clamp arm, through the clutch operatinglinkage, moves the clutch through the central or neutral position to thereverse position, causing drum 2% to rotate in a clockwise direction,and the action of drum 2% on cable 21 returns the carriage to itsstarting or rest position, ready for another workpiece. When thestarting position is reached, clamp arm 15 is intercepted by stationarymember 22. This causes clamp arm 15 to assume a vertical position,corresponding to a neutral position of the clutch, and no furthermovement takes place until the photocell is again excited. It should benoted that if, because of inertia or for any other reason the clamp armcomes to rest in a position other than vertical (neutral), the resultingslight motion of the carriage will be in the direction tending to returnthe clamp arm to the neutral position.

The clutch assembly is shown in more detail in FIG. 2. Drive pulley 23is connected to the shaft of the motor. Belt 24 passes under drivepulley 23, over forward pulley 25, the inner face of which is providedwith a friction clutch disc 34, over idler pulley 26, and under reversepulley 27, back to the starting point. Pulley 27 is also provided with afriction clutch disc 35 on its inner face. Pulleys 25 and 27 rotatefreely on shaft 28.

Between pulleys Z and 27 is drum 20, keyed to shaft 28.

Shaft 28 is arranged to slide longitudinally, causing drum 2% to contacteither pulley 25 or pulley 2.7, or to assume the intermediate neutralposition shown.

Shaft 28 terminates at one end in cap 29 within which it rotates freelyin either direction. Cap 29 is pivotaliy connected to one arm ofbell-crank 30. The latter is pivoted to a fixed point at 31, and theother end of the bell-crank is pivoted at 32 to link 33, the remote endof which is connected to clamp arm 15.

The motor, together with pulleys 23, 25, 26, and 27 operatescontinuously in the same direction. When the photocell is interrupted,and clamp arm is drawn to the right (FIG. 1), link 33 is also drawn tothe right (FrG. 2). This causes bell-crank 30 to rotate counterclockwisearound pivot 31, causing shaft 28 to move toward the opposite side ofthe carriage, and thus bringing drum in contact with disc 34 on forwardpulley and causing drum 2% to rotate counterclockwise (as seen in FIG.1). Opposite motion of the clamp arm and link brings the drum in contactwith disc 35 on pulley 27, causing the reverse action, while a verticalattitude of the clamp arm places the drum in the intermediate neutralposition.

It will be understood that the foregoing description relates to oneembodiment of the invention, and numerous alternatives will readilyoccur to those skilled in the art. For example, instead of the clampbeing mounted on a clamp arm, and the latter pivotally mounted on thecarriage, and a separate linkage connecting the clamp arm to the clutch,a single member may serve as both clamp arm and linkage, runningdirectly from the clamp to the clutch.

As shown in FIG. 3, the same result can be obtained by making use of anarrangement of bevel gears. Thus,

drive gear 36 is keyed to the motor shaft 37, and drives forward gear39) and reverse ear 3%. When the linkage to the clamp arm is pulled bythe clamp and moves to the right in FIG. 3, the bell-crank 49 turns in acounterclockwise direction, causing shaft 41 to move inward. Clutchplate 42 is keyed to shaft 4-1, as is clutch plate 43, which is used inreverse operation. Mating clutch plate 44 is keyed to a hollow shaft 46,to which is also keyed forward gear 39, so that clutch plate 44 rotatesconstantly in the same direction as forward gear 39. Shaft 41 extendsthrough hollow shaft 46, and also through hollow shaft 47, to which arekeyed both reverse gear $8 and clutch plate 45, so that clutch plate 45and reverse gear 38 rotate continuously together, in the directionopposite to the direction of rotation of forward gear 3% and clutchplate 44. Between clutch plate and clutch plate 44 is clutch frictiondisc 4-8, which serves to provide a frictional transmission of powerfrom clutch plate 44 to clutch plate 42. The friction member may be madeintegral with either clutch plate 42 or 4 2-, or two such members, oneintegral with each of the clutch plates, may be employed. The preferredarrangement, however, is that shown, in which the friction disc is adouble-faced floating member mounted to rotate freely on shaft 41.Similarly, friction disc 49 is mounted between clutch plates 43 and 45,for the same purposes.

As the bell crank 4i) rotates in a counterclockwise direction, it causesshaft 41 to move in such a way as to bring clutch plate 42, and with it,friction disc 48, into engagement with forward clutch plate 44, therebyimparting to clutch plate 42 and shaft 41 a rotation in the samedirection as that of forward gear 39.

Also keyed, or fixed in any appropriate manner to shaft 41 is powertake-off 50, which is represented in FlG. 3 as a pulley integral withclutch plate 43. Such a pulley operates in conjunction with a fixedcable in the same manner as shown in FIG. 1. Obviously, the powertake-off may be a chain-and-sprocket arrangement, or a pinion operatingin conjunction with a fixed rack, or other equivalent arrangement ifdesired.

When the linkage moves in the opposite direction, shaft 41 is caused bysuitable spring bias to move axially in the opposite direction to thatjust discussed. The spring bias is provided by spring 51 operatingthrough bell-crank 52 to urge shaft 42 to a position in which clutchplate 43 and friction disc 49 are engaged with clutch plate 45, andthereby given a rotation in the direction opposite to that imparted, inforward operation, by clutch plate 44.

The foregoing discussion relates to a preferred embodiment of theinvention in which the carriage is provided with its own drive means andcontrolled by a reversible clutch. In an alternative embodiment, theclamp may be fastened directly to the carriage in such a way that themotive power for the carriage is taken directly from the belt. Such anarrangement is illustrated in FIG. 5. in FIG. 5, the return trip isprovided for by a second clamp 6% which connects the carriage to asecond belt travelling in a direction opposite to that of belt 11.

The stacking table may be simply a flat work-receiving platform mounteddirectly on the carriage, at a level slightly below the level at whichwork-pieces are discharged from the presser or other associatedapparatus. Such a platform is indicated in dotted outline in FIG. 1.

A preferred type of stacking table, however, is that illustrated in FIG.4. As shown in this figure, the platform is provided with slots 53extending from the sides of the platform inwardly toward the center.These slots are provided in order to accommodate sides in the form ofvertical rails 54 which may be manually moved closer together to helpalign a stack of relatively narrow workpieces, such as coatsleeves orthe like, or farther apart, to help align a stack of relatively wideworkpieces, for example coat backs or entire garments. The sides may Ibe mounted in any convenient fashion, as by means of brackets on theunderside of the platform or on the carriage under the platform.Preferably, the sides are made readily demountable so that they may bereadily removed from the machine altogether when they are not needed forthe purpose of aligning and supporting a vertical stack ofuniformly-sized workpieces.

For the best and most uniform operation of the device in stacking theworkpieces discharged from the presser or other apparatus, it isdesirable to keep the top surface of the stack at a more or less uniformlevel. This may be accomplished by providing suitable means for loweringthe height of the platform in proportion as the stack of workpieces ontop of it grows in height. Various expedients may be employed for thispurpose. For example, the platform may be resiliently supported so as tobe forced down by the weight of material deposited on it. This method issomewhat limited in operation, however, because it is necessary toprovide some tension adjustment on the resilient supports to compensatefor differences in the weight-thickness ratio of different sizeworkpieces and different types of material. In practice, it is preferredto employ a device of the type illustrated diagrammatically in FIG. 7.As indicated in FIG. 7, there is provided a photoelectric sensing device55 with an associated light source 56 so positioned that the beam fromthe light source is interrupted by the passage of a stack of workpiecesin front of it, after the stack has reached a predetenmined height. Thesensing device, in turn, activates an escapement mechanism 57 whichoperating in conjunction with a ratchet 58 allows the platform of thetable to descend by a suitable predetermined amount. The result of thisoperation is to keep the top of the stack at a substantially constantlevel.

When it is desired to fold or lay up a. continuous length of material byrepeatedly doubling it back upon itself, or to handle a string ofconnected workpieces in the same manner, the embodiment of the inventionas shown in FIG. 5 is employed. In this embodiment, the presser or otherassociated apparatus is provided with a second belt 59, suitably drivenby the same drive roll and passing over some, at least, of the sameidlers as the main belt. The second belt is arranged to operate at thesame linear speed as the main belt 11, but in the opposite direction,and its function is to control the speed of the receiving platform onthe reverse run in the same manner as the main belt controls it on theforward run. To complete the arrangement, there is provided a secondclamp 60 which cooperates with the second belt in the same way as thefirst clamp 14 cooperates with the first, or main, belt. Finally, meansare provided to activate the two clamps in alternate fashion, so thatthe first clamp controls the motion of the carriage in the forwarddirection until the carriage, platform, etc. have reached apredetermined point, whereupon the first clamp 14 is disengaged from thefirst belt 11 and the second clamp 64) engaged with the second belt 59,causing the whole assembly to move in a controlled manner back to thestarting point, and the whole cycle repeated.

When operating on continuous lengths of material, the sensing functionof the photoelectric sensing device of FIG. 1, to signal the approach ofa workpiece from the presser or the like, is obviously not needed, andit is inactivated, and if desired, demounted from the machinealtogether.

The reciprocating motion of the table, as described above, is controlledby the clamps, and by the means provided to actuate one clamp anddeactivate the other, each time the carriage has reached one end of itsdesigned travel. Obviously, this actuation and deaotuation of therespective clamps may be achieved in many ways, but a particularlydesirable arrangement is that indicated in FIG. 5, in which there areprovided block members 61 and 62. to intercept a double-throw toggleswitch in such fashion that when the block nearest the feed end of thepresser or the like, i.e. block 62 intercepts the switch, the circuitenergizing the first clamp 14 is opened, causing that clamp to releaseits hold on the first belt =11, and the circuit energizing the secondclamp 60 is closed, causing the second clamp 64} to engage with thesecond belt 59, which in turn causes the carriage, table, etc. to movetoward the discharge end of the presser or the like. Similarly, when theblock 61 intercepts the toggle switch, the second clamp 6% isdeactivated, and the first clamp 14 reactivated, icausing the carriageto reverse its direction and start back toward the feed end of thepresser.

In order to control the distance of travel of the carriage, andconsequently the width of the successive courses of folded materialdeposited on the stacking table, it is desirable to provide for anadjustment in position of one or both of the intercepting blocks. Of thetwo, it is preferable that the block nearest the discharge end of thepresser, i.e. block 61 be made adjustable. In this manner, block 62 nearthe feed end of the presser can be permanently fixed at such a pointthat the carriage will travel as far as possible under the belt.Adjustment of the S6COHCl blOCi, as a moments consideration will show,then causes the carriage to move out beyond the end of the belt by onlythat amount which is needed for the length of course desired in thefolded stack. This feature is advantageous because it conserves floorspace in the shop.

in some cases, it is desired to return each workpiece, as it isdischarged from the presser or the like, to be returned to the feed end,where it can be picked up by the operator for the purpose of performinganother operation. This is accomplished by the embodiment of theinvention represented in FIG. 6. As shown in FIG. 6, the photoelectricsensing element is employed to detect the approach of a workpiecedischarged from the presser or the like, and this sensing elementinitiates the engagement of clamp 14 with the belt, and the resultingmovement of the carriage toward the feed end of the presser, exactly asdescribed with reference to the basic form of the invention as shown inFIG. 1. With respect to the invention as illustrated in FIG. 1, it willbe recalled that when the end of the workpiece passed clear of thesensing element, the clamp was deactivated and the return motionautomatically commenced.

In the device as shown in FIG. 6, however, means are provided to turnoff the energizing light, to the presence or absence of which thephotocell is responsive. The means illustrated for this purpose in FIG.6 is a toggle switch 68 and pivoted block 64, the switch being wired inseries with the light. As the approach of a workpiece is signalled bythe sensing element, the clamp is activated and the carriage starts tomove toward the feed end of the presscr, as described in connection withFIG. 1. As it does so, however, toggle switch 68, which is mounted onthe carriage, is intercepted by pivoted block 64- and the circuitopened. The result is that, even after the workpiece has cleared thesensing element, the latter responds as to absence of light-i.e. as ifthe workpiece were still the-reand continues to maintain the clampengaged with the belt. This condition, and the motion of the carriagetoward the feed end of the presser, persist until the carriage haspassed a point near the operator, where it is engaged by hook 65. Whenthis point is reached, limit switch 63 is thrown by block 62 therebydeactivating the clamp and causing the clutch to initiate the return ofthe carriage. The return of the carriage, however, is prevented by thehook, which operates on the clamp arm in a fashion similar to that ofstationary member 22 in FIG. 1, causing the clamp arm to assume avertical position and thereby disengaging the clutch. The carriage andthe stacking table therefore remain in position near the operator untilhe is ready to pick up the workpiece. When he does so, he manuallydisengages the hook, and the spring biased clamp swings to a position tothe left of vertical, engaging the clutch so as to return the carriageto its starting position near the discharge end of the presser and theremainder of the cycle is completed as described in connection withFIG. 1. On the return trip, toggle switch 68 is tripped by a secondpivoted block 66, turning the light on again, and at the end of thereturn trip, limit switch 63 is reset by block 61.

Many variations of the device according to this invention may be made tosuit the needs of particular users. For example, by reversing the springbias on the clamp arm, the apparatus may be so modified that the homeposition of the carriage is near the feed end, instead of the dischargeend, of the presser or other associated apparatus. In this as in otherrespects, while this invention has been described with respect tocertain preferred embodiments and illustrated by drawings of specificforms, these are illustrative only, as many alternatives and equivalentswill be apparent to those skilled in the art, without departing from thespirit and scope of the invention and the invention is not to beconstrued as limited, except as set forth in the appended claims.

I claim:

1. A work-receiving device for receiving workpieces discharged from aconveyor belt, said device comprising in combination a movablework-receiving platform, said platform including normally-disabled meansfor connecting said platform to said belt and causing the same to travelin a first direction at substantially the speed of said bel-t, means forsensing the approach of a workpiece toward said platform, meansresponsive to said approachsensing means for enabling saidnormally-disabled connecting means, and means for returning saidplatform in a second and opposite direction to its initial position.

2. A work-receiving device according to claim 1, wherein saidnormally-disabled connecting means comprises a clamp adapted to clamp onsaid belt.

3. A work-receiving device according to claim 1, wherein said carriageis provided with drive means independent of said belt, said drive meansbeing controlled by said normally-disabled connecting means.

4. A work-receiving device according to claim 3, wherein said drivemeans comprises a motor and a reversible clutch, said clutch beingengaged by motion of said belt transmitted through saidnormally-disabled connecting means.

5. A work-receiving device according to claim 1, wherein saidapproach-sensing means comprises a photosensitive element responsive tothe interception of light by a workpiece being dicharged from said belt.

6. A work-receiving device according to claim 5, wherein said means forreturning said platform to its initial position is actuated byrestoration of light to said photosensitive element as the end of saidworkpiece clears the same.

7. A work-receiving device according to claim 1, wherein said means forreturning said platform to its initial position comprises limiting meansindependent of said 0 as after said carriage has travelled apredetermined distance.

8. A device according to claim 2, in which said clamp means is directlyconnected to said platform, and the motive power for said platform istaken from said belt.

9. A work-receiving device for receiving workpieces discharged from aconveyor belt, said device comprising in combination a movablework-receiving platform, clamp means adapted to clamp on awork-discharging conveyor belt, said clamp means being pivotally mountedon a carriage, said work-receiving platform being mounted on saidcarriage, said pivotally mounted clamp being linked to a reversibleclutch, said pivotally-mounted clamp being spring-biased toward apivotal position different from the position toward which it is urged bysaid belt when clamped thereon, said linkage being operative to engagesaid clutch in a first sense when said clamp is in the position to whichit is urged by said belt and in a second and opposite sense when saidclamp is in the position to which it is urged by said spring bias, andto leave said clutch in a neutral, disengaged condition when said clampis in an intermediate position, motor means for driving said carriage,said motor means operating through said clutch, and traction meansoperative to transport said carriage in the direction of travel of saidbelt when said clutch is engaged in said first sense and in the oppositedirection when said clutch is engaged in said opposite sense.

10. A work-receiving device for receiving workpieces discharged from aconveyor belt, said device comprising in combination a movablework-receiving platform, clamp means for clamping on a work-dischargingconveyor belt, drive means for causing said platform to move in adirection generally parallel to said conveyor belt, reversible clutchmeans for controlling the motion imparted to said platform by said drivemeans, linkage means for causing the engagement of said clutch in aforward direction in response to changes in the position of said clampmeans relative to said platform, limiting means for disengaging saidclamp from said belt after said platform has travelled a predetermineddistance, and means for causing the engagement of said clutch in areverse direction when said clamp means is disengaged from said belt.

11. A work-receiving device for receiving workpieces discharged from aconveyor belt, said device comprising in combination a movablework-receiving platform, said piatforrn including normally-disabledmeans for causing said platform to travel in a first direction at aspeed substantially equal to and controlled by the speed of said belt,means for sensing the approach of a workpiece toward said platform,means responsive to said approachsensing means for enabling saidnormally-disabled means, and means for returning said platform in asecond and opposite direction to its initial position.

References Cited in the file of this patent UNITED STATES PATENTS1,475,802. Dorman Nov. 27, 923 2,621,927 Swift Dec. 16, 1952 2,902,888Powischill et a1. Sept. 8, 1959

11. A WORK-RECEIVING DEVICE FOR RECEIVING WORKPIECES DISCHARGED FROM ACONVEYOR BELT, SAID DEVICE COMPRISING IN COMBINATION A MOVABLEWORK-RECEIVING PLATFORM, SAID PLATFORM INCLUDING NORMALLY-DISABLED MEANSFOR CAUSING SAID PLATFORM TO TRAVEL IN A FIRST DIRECTION AT A SPEEDSUBSTANTIALLY EQUAL TO AND CONTROLLED BY THE SPEED OF SAID BELT, MEANSFOR SENSING THE APPROACH OF A WORKPIECE TOWARD SAID PLATFORM, MEANSRESPONSIVE TO SAID APPROACHSENSING MEANS FOR ENABLING SAIDNORMALLY-DISABLED MEANS, AND MEANS FOR RETURNING SAID PLATFORM IN ASECOND AND OPPOSITE DIRECTION TO ITS INITIAL POSITION.